Gamma-ray bursts are traditionally classified as short and long bursts based on their $T_{90}$ value (the time interval during which an instrument observes 5% to 95% of gamma-ray/hard X-ray fluence). However, $T_{90}$ is dependent on the detector sensitivity and the energy range in which the instrument operates. As a result, different instruments provide different values of $T_{90}$ for a burst. GRB 210217A is detected with different duration by Swift and Fermi. It is classified as a long/soft GRB by Swift-BAT with a $T_{90}$ value of 3.76 s. On the other hand, the sub-threshold detection by Fermi-GBM classified GRB 210217A as a short/hard burst with a duration of 1.024 s. We present the multi-wavelength analysis of GRB 210217A (lying in the overlapping regime of long and short GRBs) to identify its actual class using multi-wavelength data. We utilized the $T_{90}$-hardness ratio, $T_{90}-E_p$ and $T_{90}-t_{\rm mvts}$ distributions of the GRBs to find the probability of GRB 210217A being a short GRB. Further, we estimated the photometric redshift of the burst by fitting the joint XRT/UVOT SED and placed the burst in the Amati plane. We found that GRB 210217A is an ambiguous burst showing properties of both short and long class of GRBs.

The short gamma ray bursts (GRBs) are the aftermath of the merger of binary compact objects (neutron star–neutron star or neutron star–black hole systems). With the simultaneous detection of gravitational wave (GW) signal from GW 170817 and GRB 170817A, the much-hypothesized connection between GWs and short GRBs has been proved beyond doubt. The resultant product of the merger could be amillisecond magnetar or a black hole depending on the binary masses and their equation of state. In the case of a magnetar central engine, fraction of the rotational energy deposited to the emerging ejecta produces latetime synchrotron radio emission from the interaction with the ambient medium. In this paper, we present ananalysis of a sample of short GRBs located at a redshift of $z\leq 0.16$, which were observed at the late-time to search for the emission from merger ejecta. Our sample consists of seven short GRBs, which have radio upper limits available from very large array and Australian telescope compact array observations. We generate the model light curves using the standard magnetar model incorporating the relativistic correction. Using the model light curves and upper limits we constrain the number density of the ambient medium to be 10$^{-1}$–10$^{-3}$ cm$^{-3}$ for rotational energy of the magnetar $E_{\rm rot}\sim 5\times 10^{51}$ erg. Variation in ejecta mass does not play a significant role in constraining the number density.